Low-pressure irrigation systems can advantageously provide sufficient irrigation for plants while providing for efficient water consumption. One type of low-pressure irrigation system uses supply tubing having a plurality of drip irrigation devices attached thereto for delivering irrigation water to a precise point at a predetermined and relatively low volume flow rate, such as on the order of ½ gallon per hour up to about 24 gallons per hour.
A common type of drip irrigation device is a drip emitter, which can be disposed in or attached to the supply tubing. The drip emitter can tap a portion of the relatively high pressure irrigation water from the supply tubing for flow through a typically long or small cross section flow path to achieve a desired pressure drop prior to discharge at a target trickle or drip flow rate in order to irrigate a local area adjacent the drip emitter. However, it can be desirable to provide for low-pressure irrigation having a larger flow rate than the trickle or drip flow rate typically provided by a drip emitter, as well as to project the irrigation fluid beyond the local area adjacent a drip emitter. To this end, various types of “pop-up” irrigation devices have been provided for use with low-pressure irrigation systems. “Pop-up” irrigation devices are those that include a riser extensible from a housing.
One type of pop-up irrigation device which releases a relatively low volume of water over a relatively small area as compared to conventional pop-up irrigation sprinklers is disclosed in U.S. Pat. No. 5,613,802. However, this device has several disadvantages. For example, the small diameter, generally flexible body and riser may not be as robust as may be needed. Furthermore, the extensive components that must be located above ground (as shown in FIG. 2) are more susceptible to damage.
Often, nozzle bodies are attached to risers using threading. For example, internal threading on a skirt of the nozzle body can mate with external threading on an end of the riser. This permits a nozzle body to be readily attached or removed from the riser, such as for cleaning or to substitute a different nozzle body. Nozzle bodies and risers are often formed by injection molding of plastic into a mold cavity. In order to make the internal and external threading, complex geometries can be formed in the mold cavities and unscrewing mold components can be used to remove the molded components from the mold cavity. However, both can add to the cost and complexity of the mold cavity and mold equipment, thereby increasing the costs associated with manufacturing the components.